It costs $25 for a ticket to MoMa these days, but only $2.25 to see artworks by the world's leading artists in a much gloomier, rat-infested environment – the New York subway.

Since the 1980s, the city's Arts for Transit program has curated a fine collection of underground art, covered by a 1 percent budget allowance from city construction projects. Straphangers – well, pole-graspers nowadays – can spend a day zooming around in train tunnels to access museum-quality pieces like Nancy Spero's thumbs-up to empowered women, “Artemis, Acrobats, Divas and Dancers” at Lincoln Center, and Roy Lichtenstein's “Times Square Mural,” whose shotgun blasts of colors and shapes nicely complements the central station's madness.

Maya Lin, Robert Wilson and other huge art world personalities have creations lurking in the artificially lighted veins of the train system. But there are also impressive installations by artists who might not be as familiar to commuters, like Andrew Leicester's “Ghosts Series” at Penn Station, a terracotta memorial to the old rail station built by Beaux-Arts firm McKim, Mead and White. (It was knocked down in 1963, a regrettable act of destruction that helped launch the historic-preservation movement.) Then there are the 174 blackbirds, crows and grackles perched on token booths and overhead beams at Canal Street, a brooding flock of bronze arranged by Walter Martin and Paloma Muñoz. About that avian army, titled, “A Gathering,” Arts for Transit says:

They are seen roosting on railings and perched in groups, like people waiting for the train, watching, lost in thought, or chatting. Birds, the artists note, are very social creatures - just like New Yorkers, and riders may find echoes of themselves and other subway riders in their lively expressions. Canal Street is a busy commercial thoroughfare, devoid of nature. A Gathering compensates for this by enlivening the space and providing respite from the dense traffic and bustling commercialism above.

Until recently, if you wanted a statement like the above to interpret a piece of subway art, you'd have to visit the Arts for Transit website. But the agency is now touting an “officially licensed app” that gives riders “comprehensive information about the wide variety of permanent artwork installed throughout the subway and rail system in New York.”

Developed by Portland's GPS-based software company Meridian, which has mapped the cavernous interior of Powell's Books, the app allows you to scan through the city's entire collection using an artist's name or a subway line, and get podcasts explaining a handful of the artworks. There's even “turn by turn directions to great installations" once you get inside a station. Getting there might be a problem, though. Here's what “Just A. Comment” had to say about the directional functionality on the app's iTunes page,* where you can download it for free:

Planner tells one to get cross park bus at 96th/5th, get off at CPW/96 and walk. Penn is at 34th!
Why doesn't it instruct to take 5th ave 104 bus? Stops in front of hospital; goes down 5th; turns and goes over right to penn?
Every other example I tried was just as wacko.

But then there's this positive review by "Transit Mom":

This App is just what we have been looking for to learn more about NYC's great subway and rail art. It's the easiest Museum around because its always on the way, and now I have a very easy to use cheat sheet to pull up whenever my 8 y.o daughter and I want to know more about what we are looking at. Thank you Arts for Transit!!

Overall, it looks like a good, useful app. Here's hoping there will someday be a similar one for all the wonderful acts of subway-poster defacement.

* Which is based on the MTA's Trip Planner, not Meridian's directions.